Taurine nutrition and the possibility that taurine is a dietary essential for human infants have become topics of increasing interest, especially since one species, the cat, develops retinal degeneration while both cats and monkeys fail to grow maximally if dietary taurine is inadequate. A key factor contributing to the dietary requirement for taurine is the degree to which bile acids are conjugated with this sulfonic amino acid. Since newborn infants are taurine conjugators, converting to glycine shortly after birth, their taurine needs at birth may be maximal. Therefore, we propose to study the bile-lipoprotein aspect of taurine metabolism to gain insight into the potential tauring needs of infants. Because bile acid metabolism is closely linked to lipoprotein and cholesterol metabolism, the cebus monkey represents a unique primate model for investigating the taurine-lipoprotein-bile acid interrelationship since it, like the human infant, conjugates its bile acids with taurine. In addition, the cebus develops a diet-induced hypercholesterolemia that is normalized by dietary taurine. Vitamin B6 is involved in this relationship by virtue of its coenzyme involvement in the transulfuration pathway for taurine synthesis. In addition, vitamin B6 deficiency has been incriminated in atherogenesis, although its association with taurine and hyperlipemia has not been defined. Thus, this proposal would examine the taurine/B6 nutrition of cebus monkeys to model the taurine-lipoprotein-bile relationship in man, especially as it pertains to the newborn. The specific aims include definition of the taurine/B6 deficient-hyperlipemia in terms of lipoprotein characterization and turnover, bile metabolism including synthesis, secretion, pool size and distribution of bile acids, as well as the lithogenic index. We would also estimate the relative conversion of lipoprotein or newly synthesized cholesterol into bile sterols. The results will answer important questions concerning the role of taurine in bile metabolism and lipoprotein clearance and define the relationship of vitamin B6 in that process. An appreciation of this relationship will provide needed insight into a possible requirement for taurine by human infants.